On the Mark: Frame construction

Continued...

Layout area/work table

You will spend a lot of time working on the plans
and frames. If possible, use an elevated work table as I did. This saves a lot
of wear and tear on the back and knees. This is practical for boats up to ~
20-24 feet. Above that you will need to work on the floor as you will exceed an
arm's reach and would need to climb up on it anyway. I used a 3/4"
thick 4'x8' sheet of melamine coated particle board (~$35) propped up
on 2 barrels (saw horses would work as well).

The melamine provides a nice smooth surface to
trace onto. The lines show up clearly and have lots of contrast. The smooth
surface helps in creating good tracings on the reverse side of the plans.

Tracing on Table

The table and the back of the plans need to have
the frame outlines traced onto them. This is done by laying the plans on the
table with 2 layers of carbon paper sandwiched in between. 1 layer faces up to
mark the back of the plans and the other faces down to mark the table. Be sure
to tape the plans down prior to tracing. You can either use drafting tape (hard
to find low tack masking tape) or other low tack / easy to remove tape (I like
the 3M blue masking tape). I did the tracing with a 0.5 mm mechanical pencil
with a HB lead.

Unless you are far steadier than I am (younger and
don't drink coffee), the tracings will be greatly improved if you use a
straight edge or large French curve to guide your pencil. The curves are not
very tight and if you use a straight edge (I liked using the back edge of a
hacksaw blade as shown in the photo), the piecewise linear lines (each section
1-2" long) makes a very good and accurate representation of the frame
curves. The hacksaw blade is light and the teeth provide just enough friction
to keep it from slipping accidentally as you trace.

When tracing on the table, be sure to allow room
for the other half of each frame at assembly time.

The melamine is on both sides of the board. I
flipped it over half way through to have a fresh work surface and eliminate
confusing lines.

One pack of carbon paper (yes they still sell it at office supply stores)
will last the entire project and then some. Glen-L has large size carbon paper,
so you don't have to handle the individual sheets (Transfer
paper). When laying out the sheets don't worry if they overlap, 1 extra
layer won't hurt.

Transferring frame pieces to wood

Mark each set of frame outlines with a circle or
other indication of the frame you are about to trace. Check off each section on
the plans as you trace it. Since you need to stop and reposition the plans for
each board, it is easy to get confused and trace the wrong item. You don't
want to be assembling the sides of frame 4 onto the rest of frame 5 (this would
only happen if frame 4 is already complete as well).

Clamp your longer pieces down (such as carlings)
prior to tracing. Lay the carbon paper on the wood and tape the plans down to
the piece of wood. Prior to tracing, run your finger around the plan lines to
make sure nothing has shifted and all of the plan for that piece lands on the
wood. Of course if it slips, the last part to be traced is the part not on the
wood.

Once again use an edge guide. This tracing IS THE
SHAPE of the hull. If you are not accurate now and in the next steps, you will
have a LOT of fairing to do later. At this point, we want the lines transferred
with <1/16" accuracy.

When I talk about striving for high levels of
accuracy at this stage, don't let it scare you off, but instead look to the
points mentioned as pointers to what is important for later stages. For
example, the inside of the frame edges has nothing to do with the hull shape.
If you want to leave it rough, go ahead (but please figure out a way to cover
it up).

Cutting and sanding

Click to
enlargeSides ready to be cut. Note how
piece is laid out so that it is traced
around the knot on the rear (top) piece.

If you have access to a band saw, sawing these
pieces is relatively easy. Use a 1/2" 3-4 TPI (tooth per inch) skip tooth
blade. The stacked wood is then fed through. The 1/2" blade evens out the
curves and provides a fair cut. The skip tooth blade clears out he sawdust well
and leaves a clean enough finish that it will sand easily.

While the pairs are still together, sand the edges.
You want a matched set and this is the way to do it. Use a large belt sander or
drum sander (for the inside curves). The outside edges must be square. If you
tip the piece, the 2 parts will no longer be identical. It is much easier to
keep the piece square with both parts held together, due to the wider working
area. Do not sand so far that you remove the lines. Sand to the lines, not
through them.

Make use of the knotty or curved grain pieces for
the frames. Arrange the pattern so that the wood grain flows with the curves
for greatest strength. I used all #1 Common wood for the frames. Since the
pieces are not all that big, you can easily work around the knots. At the mill
where I buy my wood, the savings over select is ~40%. Save your clear straight
pieces for the battens, chines and sheers. In addition, the #1C wood may have a
clear edge which is suitable for battens if ripped off prior to cutting to
length.

If you have access to a power miter box (chop saw),
radial arm saw or table saw, the angled ends of the corners may be cut there
with some improvement in accuracy. Transfer the angle with a bevel gauge as
shown. The enlarged photo also shows the plans flipped on the table, ready for
frame alignment.

Prior to assembly, sand the faces as well to remove
the planer marks. 80 grit is fine and provides a nice "tooth" for the
epoxy to hold into.